/**
 * Definition for singly-linked list.
 * public class ListNode {
 *     int val;
 *     ListNode next;
 *     ListNode() {}
 *     ListNode(int val) { this.val = val; }
 *     ListNode(int val, ListNode next) { this.val = val; this.next = next; }
 * }
 */
class Solution {
    public ListNode mergeTwoLists(ListNode list1, ListNode list2) {
        if(list1==null)
        {
            return list2;
        }
        else if(list2==null)
        {
            return list1;
        }
        else if(list1.val >= list2.val)
        {
            list2.next=mergeTwoLists(list2.next,list1);
            return list2;
        }
        else
        {
            list1.next=mergeTwoLists(list1.next,list2);
            return list1;
        }
    }
}